Even though this thread is 10 years old and you probably have this info now, here is the information about the Ambrose Brantley McKee who was my great great grandfather's younger brother.
Ambrose Brantley McKee was born in either 1834 or 1836 in Alabama to Ambrose and Martha (Patsy) McKee. He died in 1900. I believe there may be military records available for him through Fold3.com.
He should also be listed in the household with Ambrose and Patsy in the 1850 census. He is listed not as Brantley but as Ambrus in the 1850 Census. By 1860 he was no longer listed as being in their household, but I suspect would be listed as head of household himself.
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